1. Which of the following motors can be used for unity power factor ? (a) Capacitor run motor (b) Shaded pole motor (c) Hysteresis motor (d) Schrage motor 2. When a D.C. series motor is connected to A.C. supply, the power factor will be low because of (a) high inductance of field and armature circuits […]
1. In a split phase motor, the running winding should have (a) high resistance and low inductance (b) low resistance and high inductance (c) high resistance as well as high inductance (d) low resistance as well as low inductance 2. If the capacitor of a single-phase motor is short circuited (a) the motor will not
1. Reduction in core losses and increase in permeability are obtained with transformer employing (a) core built-up of laminations of cold rolled grain oriented steel (b) core built-up of laminations of hot rolled sheet (c) either of the above (d) none of the above 2.In a power or distribution transformer about 10 pm cent end
1. The reactance of a transformer depends on (a) size of the core (b) size of the tank (c) leakage flux (d) all of the above. 2. Which winding of the transformer has less cross-sectional area ? (a) Primary winding (b) Secondary winding (c) Low voltage winding (d) High voltage winding 3. Which of the
1.A voltage transformer of which class of accuracy can be used for precision testing in standard laboratories? (a) 0.1 class (b) 10 class (c) 5.00 class (d) 1000 class 2. In a transformer the tappings are generally provided on (a) primary side (b) secondary side (c) low voltage side (d) high voltage side 3. The
1. In a 50 kVA transformer the number of turns in the primary and secondary windings are 834 and 58 respectively. If the primary is connected to 3300 V supply the secondary current will be (a) 15 A (b) 30 A (c) 218 A (d) 238 A 2. If full load copper loss of a
1. In a power transformer (a) primary winding is closer to core (b) secondary winding is closer to core (c) low voltage winding is closer to core (d) high voltage winding is closer to core 2. In a transformer, the magnetic coupling between primary and secondary circuit can be increased by (a) increasing the number
A current limiting reactor is a coil which has a large inductive reactance in comparison with its ohmic resistance. It consists of a few turns of heavy copper strip, sometimes cast directly in concrete so that it can withstand large stress developed by the fault currents. Generally, the reactance of the power system under fault
There are two types of extrinsic semiconductors. These are n-type and p-type. In n-type, the electrons are majority charge carriers while holes are minority charge carriers. In p-type, the holes are majority charge carriers and electrons are minority charge carriers. When these two types of materials namely n-type and p-type are chemically combined with a special
A fuel cell is defined as an electrochemical device that continuously converts the chemical energy of fuel into electricity and heat without combustion. Difference between Fuel Cell and Battery: A fuel cell is similar to other electrical cells (battery) in respect that both have the positive and negative electrodes with an electrolyte between them and